BRIEF OHNE UMSCHLAG Baedeker, Julius Author: Baedeker, Julius Recipient: Haeckel, Ernst Dating: 09.02.1894
BRIEF OHNE UMSCHLAG Bormann, Edwin Author: Bormann, Edwin Recipient: Haeckel, Ernst Dating: 16.02.1894
BRIEF OHNE UMSCHLAG Fischer, Gustav Author: Fischer, Gustav Recipient: Haeckel, Ernst Dating: 15.02.1894